protect or unprotect a locked cell with formula

Hi Beautiful people of the Excel World.

So, I am hoping this is possible - I need a formula or something that will give a cell protection or unprotection based on what is in another cell.
For example, I have products of which some can allow for custom sizes, and some that cannot, so if the user enters the product code for an item in Cell B13, cell S13 will return a lookup result that states if that item will allow for special sizes. Cell H13 needs to be the cell in which the user can add the custom size if the item allows for it, so needs to unprotect itself based on the result in cell S13.

Another point to note, is that the worksheet is locked so users cannot mess with it.

Hoping it's possible, and that someone can help...

This could be done with Data Validation using a custom formula, although it is not protection or unprotection (that is why we ask members to describe the problem, not the solution).

What does S13 look like? Let's suppose it is Yes for allowing custom sizes, and No for not allowing them. Then H13 would have a Data Validation formula that says

=S13="Yes"

If S13 is not Yes, then Data Validation will not allow any entry to H13 and will show the user an error message. You can tailor this message when setting up the data validation.

If you need more detailed help with this, please attach your file. Under the text box where you type your reply click the Go Advanced button. On the next screen scroll down and click on Manage Attachments, which will show a pop-up window to Select and Upload a file. Then close the window.

You might be able to do it with Data Validation. Otherwise, you'd probably need VBA.

Originally Posted by 6StringJazzer

This could be done with Data Validation using a custom formula, although it is not protection or unprotection (that is why we ask members to describe the problem, not the solution).

What does S13 look like? Let's suppose it is Yes for allowing custom sizes, and No for not allowing them. Then H13 would have a Data Validation formula that says

=S13="Yes"

If S13 is not Yes, then Data Validation will not allow any entry to H13 and will show the user an error message. You can tailor this message when setting up the data validation.

If you need more detailed help with this, please attach your file. Under the text box where you type your reply click the Go Advanced button. On the next screen scroll down and click on Manage Attachments, which will show a pop-up window to Select and Upload a file. Then close the window.

Hi.

Thanks for your response.
Okay, so to be more clear:

The user adds a product code to unprotected cell B13,
Protected Cell C13 shows the products description from VLOOKUP,
Cell S13 is hidden, and does not form part of the visible sheet, but returns a result of either 'YES' or 'NO', determining if the item allows custom sizes or not,
Cell H13 should be locked UNLESS cell S13 result='YES', which will then allow the user to enter their own specified dimensions into cell H13 if that item allows it. (Eg, standard might be 600, and the user can then add their own, eg 647 or 732 etc) The user needs to be able to add whatever number they so desire, so a pre-defined DV list to select from would not work.

Hope this helps.

Data Validation will probably do all that for you. Did you play around with it at all yet?

Also, it would probably help if you upload a small (clean) sample workbook (not a pic) of what you are working with, and what your expected outcome would look like.